Allyl monomers such as allyl alcohol and allyl acetate are well known. Allyl alcohol is readily available, for example, by isomerizing propylene oxide in the presence of a lithium phosphate catalyst. Allyl alcohol has been widely used to make certain allyl derivatives such as diallyl phthalate and diethylene glycol bis(allyl carbonate). Heating allyl monomers in the presence of free-radical initiators commonly gives products of relatively low molecular weight. In addition, allyl monomers are quite unreactive compared with other ethylenically unsaturated monomers. Typically, attempted polymerizations result in slow reactions and low monomer conversions. (See: Kirk-Othmer, Encyclopedia of Chemical Technology, (1982), Volume 2, "Allyl Monomers and Polymers," pp. 109-128.)
Polymers made by polymerizing allyl monomers such as allyl alcohol, allyl acetate, methallyl alcohol, and propoxylated allyl alcohol are generally not commercially available. Poly(allyl alcohol) is known, but its usefulness is rather limited by its poor solubility in most common organic solvents. Usually, allyl polymers are made by charging the allyl monomer and a free-radical initiator to a reactor, and heating the mixture at a temperature effective to polymerize the monomer. All of the free-radical initiator is charged at the start of the polymerization. Conversions of allyl monomer to polymer obtained by this process are typically less than about 20%. The polymerization of allyl acetate in bulk as described in Sandler et al., Polymer Syntheses, (1980), Volume III, Chapter 8, "Polymerization of Allyl Esters," pp. 263-266, illustrates processes used to polymerize allyl monomers.
Still needed in the art are improved processes for making allyl polymers and copolymers. A preferred process would give higher conversions of the relatively unreactive allyl monomers to reduce the need for recycling unreacted monomers. Ideally, the process would be cost-effective and easy to perform.